Method for producing a thermoplastic elastomer material

ABSTRACT

A method for producing a thermoplastic elastomer material in the form of a mixture of one or more thermoplastics and one or more crosslinked rubbers. Said mixture contains the following constituents: one or more thermoplastics for 10-90%, one or several non-crosslinked rubbers, a crosslinking activator, a crosslinking agent, possibly other additives. Said process involves the use of a roll system characterized by the following process steps: the thermoplastic(s) and/or the non-crosslinked rubber(s) are introduced into the roll system through the feeding opening in the absence of the crosslinking agent and are subsequently melted and dispersed with formation of a homogenous mixture; the homogenous mixture is conveyed in the roll elements at the same time as the crosslinking agent is delivered to a transition area in the roll elements; the mixture provided with the crosslinking agent is dispersed and homogenized at the same time as vulcanization at high extension rates with formation of the thermoplastic elastomer material. The calendered surface amounts to ≧75 m 2  thermoplastic elastomer per kilo in relation to the totality of roll elements. Another variation of the method is also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a process for producing a thermoplasticelastomer compound (TPE) in the form of a mixture of one or a pluralityof thermoplastics and one or a plurality of crosslinked rubbers, such amixture being produced from

one or a plurality of thermoplastics in an amount of from 10 to 90% byweight;

one or a plurality of rubbers;

a crosslinking activator;

crosslinking agents, as well as

other additives, if required;

with the use of a roll system comprising a feeding opening of aconveying screw feeding the first roll element, as well as additionalroll elements with point for adding other materials within a transitionarea of the roll elements, whereby each roll element has a main spindle(central spindle) and a plurality of rotating spindles, and whereby,furthermore, the components of the mixture are fed into the roll systemvia the feeding opening and the points for adding other materials.

2. The Prior Art

The elastomer compound of the type specified above is a blend consistingof a thermoplastic material and a crosslinked rubber. Crosslinking ofthe rubber is carried out by dynamic vulcanization. The term “dynamicvulcaniztion” is understood to be a process in which the thermoplasticmaterial, the rubber and the crosslinking system are masticated (meltedopen and dispersed) as the rubber is being crosslinked. Examples ofdynamically crosslinked thermoplastic elastomers and the process ofdynamic vulcanization are described in U.S. Pat. Nos. 4,130,535 and4,311,628. German laid-open patent specification 26 32 654 describes ablend consisting of a thermoplastic polyolefin, an EPDM rubber and anydesired crosslinking system known from U.S. Pat. No. 3,806,558. Therubber is vulcanized to such an extent that it contains no more thanabout three percent of rubber extractable in cyclohexane at 23° C.Furthermore GB-A-2 007 683 describes a thermoplastic elastomercontaining a thermoplastic crystalline polyolefin resin and vulcanizedEPDM. Crosslinking of the rubber is carried out in a phenolic resin. Thedegree of crosslinking so obtained exceeds 97%. It is pointed out in EP0 107 635 B2 that the blending methods employed conventionally up untilthat time for producing the dynamically vulcanized thermoplasticelastomers are not suitable for producing soft mixtures with goodextrudability. Said document describes a one-stage process carried outon a double-screw extruder with screws rotating in the same sense,which, at high shearing rates of >2000 s⁻¹ and with a dwelling time of<2 minutes permits the manufacture of soft thermoplastic elastomers withgood extrudability. Masticating of the rubber and other components takesplace in the first third of the double-screw extruder. Dynamicvulcanizing takes place in the last two thirds. A similar process forthe production of a dynamically vulcanized thermoplastic elastomer isdescribed in EP 0 072 203 A2, where in a one-stage process carried outon a double-screw extruder with screws revolving in the same sense, apartially crosslinked thermoplastic elastomer is produced from aperoxidically crosslinkable olefinic copolymer rubber, a polyolefinresin not degradable by peroxide, and an organic peroxide. Thecomponents of the mixture are directly admitted into the double-screwextruder. Furthermore, EP 0 547 7843 A1 describes a one-stage processfor producing a dynamically vulcanized thermoplastic elastomer, wherebyan olefinic copolymer rubber and a thermoplastic polyolefin are heredirectly fed into a blending extruder. An organic peroxide is addedfarther downstream in the direction of flow in the plasticizing unit.The shear rate of the dynamic vulcanization is >500 s⁻¹. Single-screw,double-screw or multiple-screw extruders can be employed for theprocedure described in said document.

The mixing methods known heretofore for producing a dynamicallycrosslinked thermoplastic elastomer are afflicted with the followingproblems:

It is not possible with a kneader (inner mixer) to achieve adequatedispersion and homogenization in the course of dynamic vulcanization ofthe elastomer phase. High shear rates can be achieved only inadequatelyor not at all due to the circumstances described in EP 0 107 635 B2. Theproduction of soft blends with good extrudability is not possible withthis process.

A double-screw extruder with screws revolving in the same sense iscapable of assuring sufficient dispersion and homogenization. Theproduction of soft, well-extrudable thermoplastic elastomers with adynamically crosslinked elastomer phase is admittedly possible with thisprocedure; however,high shear rates of >2000 s⁻¹ are required. Such highshear rates and the mechanical energy introduced thereby in the plasticmaterial are converted into heat, which leads to a considerable rise ofthe mean temperature of the melt in general and, in detail, totemperature and viscosity inhomogeneities because of the poortemperature conduction values. The high admission of energysimultaneously combined with rising mass temperatures leads to increasedmaterial stress, or even degradation of the material. Because of thesurface conditions it is not possible with the known twin-screw extruderwith screws revolving in the same sense to discharge again the admittedenergy by means of the cooling system available, and to permit carefuldispersion and homogenization in the course of dynamic vulcanization ofthe rubber phase. Fitting the pair of screws with conveying, mixing andkneading elements thus always constitutes a compromise between theadmission of energy and the increase in mass temperature of the melt.

SUMMARY OF THE INVENTION

Now, the invention has as an object to provide a careful process forproducing dynamically vulcanized thermoplastic elastomer compounds thatpermits very good dispersion and homogenization of a dynamicallycrosslinked thermoplastic elastomer with enhanced temperature control inthe course of dispersion and dynamic vulcanization, combined with theresult that thermoplastic vulcanisates with enhanced properties areobtained.

The process steps of the two variations essential to the invention aredescribed as follows:

Variation A

The thermoplastic/thermoplastics and/or non-crosslinked rubber/rubbersare fed into the roll system via the feeding opening in the absence ofthe crosslinking agent, and are subsequently melted open and dispersed,with formation of a homogeneous mixture.

The homogeneous mixture is transported in the roll elements while thecrosslinking agent is simultaneously added in a transition zone of theroll elements; and

the mixture provided with the crosslinking agent is dispersed andhomogenized as the vulcanization is being carried out simultaneously atexpansion rates of 100 to 1500 s⁻¹, especially 500 to 1500 s⁻¹, withformation of the thermoplastic elastomer compound.

Variation B

The thermoplastic/thermoplastics and/or the crosslinked rubber/rubbersand the crosslinking agent are jointly fed into the roll system via thefeed opening, and are subsequently melted open and dispersed; and

the mixture is dispersed and homogenized at expansion rates of 100 to1500 s⁻¹, especially 500 to 1500 s⁻¹, as vulcanization takes place atthe same time, with formation of the thermoplastic elastomer material.

Furthermore, it is important in connection with either process variationthat the calendered surface area per kilogram thermoplastic elastomercompound amounts to ≧75 m², particularly ≧100 m², in particular again to100 to 300 m² based on the totality of roll elements.

According to both variations, the crosslinking activator and theadditives such as, for example plasticizing oils, fillers, reinforcingagents, processing aids, anti-ageing agents, internal and externallubricants, if any, can be admitted into the roll system by way of thefeeding opening or via another feeding point, whereby it is useful inconnection with variation A if the crosslinking activator is admittedbefore the crosslinking agent is added.

If, within the framework of said two variations, only the thermoplasticmaterial is fed into the roll system via the feeding opening, thenon-crosslinked rubber can be admitted into the roll system by way ofanother feeding point. The same applies vice-versa, if onlynon-crosslinked rubber is first fed into the roll system via the feedingopening.

The novel process technology is described in detail in the following byway of example with the help of test results.

The process prepares the thermoplastic elastomer material in the form ofindividual kneaded beads, whereby effects are achieved similar to thosin rolling mills. Characteristic of the process as defined by theinvention is the excellent dispersion and exact temperature control. Asopposed to the known single-, double- or multiple-scew extrudersemployed in the production of thermoplastic vulcanisates, where theactive flank of the screw transports the material in the direction ofthe outlet opening, the transport of the material is achieved in thepresent case through the axial forces generated when revolving toothedspindles engage a toothed main spindle. The toothing may have a pitchangle of 10° to 80°, in particular of 45°. The revolving spindles aredriven by the rotation of the main spindle. Furthermore, as opposed tosingle- or double-screw extruders, in which a relatively compact bed ofsolids has to be melted open, an introduction of heat takes place in theprocess as defined by the invention, such admission of heat being veryclose to the introduction of heat in the processing in rolling mills.The special suitability of the process as defined by the invention forproducing theroplastic vulcanisates results from the special flowconditions in the planetary part, in addition to the large surface areaswhere heat is to be exchanged. The material present in the cross sectionof the tooth is forced through the narrowing of the cross section of theflank gaps. The 45° toothing assures that a pressure maximum alwaysdevelops only in points along the revolving spindles. Due to the smallcross section in the head clearance of the toothing, locally high flowrate prevail there, which lead to good dispersion, homogenization andexcellent flushing of the tooth base.

It has been found within the framework of tests that excellentdispersion of the vulcanized rubber phase is obtained if 1 kilogram ofthe thermoplastic elastomer mixture is rolled out throughout the entireprocess as defined by the invention to a surface area of 75 m² to 300m². Preferred are in this connection surface areas of 100 to 300 m² perkg TPE.

BRIEF DESCRIPTION OF THE DRAWINGS

The diagram shows the particle division as a function of the form offlow (curve 1 for pure shear flow; curve 2 for biaxial extension flow)and the viscosity ratio of the dispersed phase in relation to thecontinuous phase. Further division of the dispersed phase is possible aslong as the Weber number W_(e) is greater than a critical Weber numberW_(e) critical

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

$W_{e} = {{\frac{{\eta_{CP}\left( \overset{.}{\gamma} \right)} \cdot \overset{.}{\gamma} \cdot R}{\sigma_{12}} > {W_{e\quad {crit}} \cdot W_{e}}} = {f\quad \left( {{{flow}\quad {form}},\quad \lambda_{1}} \right)}}$

In summary, the individual parameters have the following meaning:

W_(e)=Weber number

η_(CP)=viscosity of continuous phase (=thermoplastic in the presentcase)

η_(DP)=Viscosity of disperse phase (=rubber in the present case)

λ₁=ratio of viscosities

{dot over (γ)}=shear rate

σ₁₂=interface tension

R=radius of disperse phase (=rubber in the present case)

W_(e crit) is plotted in the diagram as the ordinate. Distinctly lowercritical Weber numbers are obtained for the represented λ₁ viscosityratio range (abscissa) for biaxial extension flows.

Said representation shows that especially the extension flows causedwhen the toothed revolving spindles engage the toothed main roll lead tomore extensive division of the vulcanizing rubber particles.

With pure shear flow, particle division is possible only in a viscosityratio range of disperse phase to continuous phase of about0.1<η_(DP)/η_(CP)<4, namely in accordance with the area above curve 1(=dispersion). Further division of the vulcanizing rubber particles ispossible only with extension flows as present in the process as definedby the invention, namely in accordance with the area above curve 2(dispersion). No dispersion, however, is possible below curves 1 and 2.

In the process as defined by the invention, the vulcanized thermoplasticvulcanisates with enhanced properties are treated with extension ratesbetween the base of the tooth and the bridge of the tooth in the rangeof 100 to 1500 s⁻¹, particularly in a range of between 500 and 1500 s⁻¹.

Furthermore, it was found in the tests that the rate of reaction in thecourse of the dynamic vulcanization is highly dependent in a decisivemeasure on the introduced comparative tensions and the surface area ofthe processing set of machines rolled out per rotation. The process ofthe present invention produces per rotation, in a comparable period ofdwelling time, a surface area larger by factor 2.5 to 3 than possiblewith single- or twin-screw extruders of the type employed at the presenttime.

In particular, the large rolled-out surface areas, in association withthe high comparative tensions caused by the high extension rates, leadto a distinct increase in the crosslinking rate.

The following vulcanization times were determined in the set of machines(inside mixer, double-screw extruder, planetary roll extruder) employedin this treatment for a preferred degree of crosslinkage of the rubberphase of >90%. The degree of crosslinkage was determined by dissolvingin cyclohexane at room temperature. The blending formula and the processparameters are summarized in tables 1 and 2, respectively. In parallel,the vulcanization time of the formula without thermoplastic materialspecified in table 1 was determined in a vulcameter. In this connection,t_(v90)=the time for a vulcanization reaction of 90%.

Vulcameter t_(v90) = 9 minutes Inside mixer t_(v90) = 4 minutesTwin-screw extruder t_(v90) = 0.5 to 0.7 minute Planetary roll extrudert_(v90) = 0.2 to 0.4 minute.

Due to the large surface area rolled out per rotation of the mainspindle, and the high number of place change processes connectedtherewith, it is possible with the process as defined by the inventionto distinctly reduce the dwelling time required for vulcanizing therubber phase, as compared to the existing process techniques. Theminimum dwelling time in the presence of the crosslinking activator andthe crosslinking agent amounts to less than 60 s, preferably to 10 to 30s.

The thermoplastic elastomer compounds produced with the process asdefined by the invention preferably have a degree of crosslinkage of therubber phase of >90%,

A roll system that is suitable for carrying out the process as definedby the invention is described in patent documents DE 91 11 406 U1, DE 3725 641 C2, DE 37 12 749 C1, and DE 27 19 095 C2. Particularly suitableis a roll system according to DE 39 08 415 A. In the roll unit, both themain spindle and the cylinder jacket comprise liquid tempering, wherebythe temperature can be effectively controlled especially withpressure-superposed water.

The process as defined by the invention was carried out within theframework of a test on a roll system preferably in the following way:

A planetary roll system of the firm ENTEX TP-we 70 M3 was employed inthe tests. In general, any planetary roll system permitting the dwellingtimes and extension rates required for said process is suitable. Therubber, the thermoplastic material and additional powdery mixingcomponents were fed to the feeding opening of a conveyor screw feedingthe first planetary roll element. As rubber, 200 pbw (parts by weight)of an EPDM extended with 100 parts oil was used (Keltan 509×100 DSM).The ethylidene-norborne component came to 8% by weight. As thermoplasticcomponent, 50 pbw of a polypropylene homopolymer with an MFI=0.7 wasused (Moplen Q 30 P from Montell). 20 pbw of a calcined kaolin was addedas filler (Polestar 200 R from ECC). 0.5 pbw Irganox 1010 (supplied byCiba Additive GmbH) was metered in as anti-aging agent. Furthermore, 0.5pbw zinc stearate (SM 101 supplied by Peter Greven) was added. 2 pbwzinc oxide active (from Bayer AG) and 1 pbw salicylic acid (from HinrichTietjen) was added as crosslinking activator. Possibilities for addingliquid and solid components are available in the transition zonesbetween the first and second as well as every further planetary rollelements. Within the framework of the tests, the crosslinking agent wasadded according to the process variation “A” between the first andsecond roll elements. In the present case, the crosslinking agent was asolution of 5 pbw phenolic resin (Schenectady SP 1045 from Krahn Chemie)and 5 pbw of a paraffinic plasticizer (Sunpar 150 from Sunoil), wherebythe solution was injected into the melt. In general, any other knowncrosslinking agent can be added to the rubber/thermoplastic melt;however, any such agent has to be suitable for the selected rubber.Also, crosslinking of the rubber phase with peroxides can be carried outparticularly advantageously with the process as defined by theinvention.

Owing to the short dwelling times and the exact temperature control inthe course of the dynamic vulcanization it is possible to obtainthermoplastic vulcanisates with enhanced properties of the continuouspolypropylene phase. This results from a lower degradation of thepolypropylene by radicals originating in the process.

The dynamic vulcanization of the rubber phase takes place in the twoplanetary roll elements downstream. An amount of plasticizer oildepending on the desired hardness is added to the melt between thesecond and third roll elements. For a thermoplastic vulcanisate with aShore-A hardness of 75, 15 pbw of a paraffinic plasticizer (Sunpar 150supplied by Sunoil) was injected.

The melt is advantageously degassed under vacuum at the end of the thirdroll element. Granulating is subsequently carried out after the lastroll element.

The dwelling time of the test mixture came to only 20 s at a speed(rpm's) of the central spindle of 140 min⁻¹ and a through-put rate of105 kg/h. The length of the central spindle for the test roll systemamounted to 1200 mm. In general, the central spindle may have a lengthof from 0.5 to 6 m. The planetary roll elements of the employed rollsystem were provided with water tempering. The coil conducting the flowof water is integrated in the surface of the roll cylinder. The masstemperature of the course of dynamic vulcanization amounts to 0 to 70°C., preferably 10° to 50° C. above the melting temperature of thethermoplastic material.

With the test mixture and in the preferred process, a mass temperatureof 200° to 210° C. was measured on the outlet of the past planetary rollelement. The mass temperature was measured with a thermometer insertedin the mass. Said mass temperature, therefore, is by 35° to 45° C. abovethe melting temperature of the polypropylene (Moplen Q 30 P supplied byMontell). Comparable tests carried out on a twin-screw extruder with ascrew diameter of 40 mm and at screw speeds of from 350 to 450 min⁻¹ ledto mass temperatures of 240° to 290° C.

The blending formula (table 1) and the process parameters (table 2) aresummarized again within the framework of a final overview, in connectionwith the following explanations:

a=inner mixer

b=double-screw extruder (Berstorff ZE 40)

c=planetary roll extruder (ENTEX TP-WE 70 M3)

Vulcanizing time: This is the time for vulcanizing the rubber phase,measured from the time the crosslinking agent is added until thematerial exits from the processing machine. For the double-screwextruder and the planetary roll extruder, the minimum dwelling timeswere determined after the crosslinking agent was added.

Shore A according to DIN 53505 Ultimate tensile strength according toISO 527 Elongation at rupture according to ISA 527 Pressure deformationtest ASTM D 395 B Test conditions: 25%, 70° C., 22 h, 30 min.

TABLE 1 Keltan 509 × 100 200 pbw 66.90% by wt. Moplen Q 30 P 50 pbw16.70% by wt. Polestar 200 R 20 pbw 6.79% by wt. Sunpar 150 20 pbw 6.70%by wt. Zinc oxide, active 2 pbw .67% by wt. Zinc stearate .5 pbw .16% bywt. Irganox 1010 .5 pbw .16% by wt. Salicylic acid 1.0 pbw .32% by wt.Resin SP 1045 5.0 pbw 1.69% by wt. Sum 299 pbw 100.00% by wt.

TABLE 2 a b c Diameter [mm] — 40 70 Volume [liter] 1.2 — — Length [L/Dor mm] — 48 1200 Speed [min⁻¹] 150 400 140 Vulcanization time [s] 240 3515 Through-put [kg/h] 8 73 105 Mass temperature [C. °] 215 280 210 ShoreA [SHE] 75 71 74 Ultimate tensile strength [N/mm²] 4.8 4.6 5 Elongationat break [%] 220 296 320 Pressure deformation test [%] 45 48 40

What is claimed is:
 1. A process for producing a thermoplastic elastomermaterial in the form of a mixture of at least one thermoplasticelastomer compound and at least one crosslinked rubber, said mixturebeing produced from the following mixture components comprising: atleast one thermoplastic in an amount of 10% to 90% by weight; with thebalance up to 100% by weight of at least one crosslinked rubber; acrosslinking activator; and a crosslinking agent; with the use of a rollsystem comprising a feeding opening of a conveyor screw feeding thefirst roll element, additional roll elements with feed points in atransition area of the roll elements, whereby each roll element has amain spindle and a plurality of revolving spindles, whereby the mixturecomponents are fed into the roll system via the feeding opening and thefeed points, comprising the following process steps: feeding thethermoplastic or the crosslinked rubber into the roll system in theabsence of the crosslinking agent via the feeding point and subsequentlymelting and dispersing with formation of a homogeneous mixture;transporting the homogeneous mixture in the roll system whilesimultaneously adding the crosslinking agent in a transition area of theroll elements; dispersing the mixture provided with the crosslinkingagent and homogenizing the mixture as vulcanization is simultaneouslytaking place at extension rates of 100 to 1500/s with formation of thethermoplastic elastomer material; whereby the calendered surface areaper kilogram of thermoplastic elastomer compound amounts to ≧75 m² basedon the totality of roll elements.
 2. The process according to claim 1,comprising adding the crosslinking activator before the crosslinkingagent is added.
 3. The process according to claim 1, wherein thecalendered surface area per kilogram of thermoplastic elastomer compoundamounts to ≧100 m²; and wherein said thermoplastic elastomer compound ispolypropylene.
 4. The process according to claim 1, wherein the divisionof the crosslinking rubber particles takes place at a value ofη_(DP)/η_(CP)≧4 due to highly expanding flows as the revolving spindlesengage the screw base of the main spindle; whereby η_(DP) is theviscosity of the disperse phase and η_(CP) is the viscosity of thecontinuous phase.
 5. The process according to claim 1, wherein theextension rates amount to 500 to 1500 s⁻¹.
 6. The process according toclaim 1, wherein the dwelling time of the mixture amounts to ≦60 s,based on the totality of roll elements.
 7. The process according toclaim 1, wherein the crosslinking time of the rubber amounts to ≦30 s.8. The process according to claim 1, wherein the temperature of thethermoplastic elastomer compound at the time of exit of the compoundfrom the last roll element does not exceed the melting temperature ofthe thermoplastic material by more than 70° C.
 9. The process accordingto claim 1, wherein the roll system has an overall length of 0.8 to 6 mbased on the totality of roll elements.
 10. The process according toclaim 1, wherein the rubber is crosslinked to an extent such that notmore than 10% by weight of the rubber is soluble in a rubber solvent;and wherein the dwelling time of the mixture ranges from 10 to 30seconds based on the totality of roll elements.
 11. The processaccording to claim 1, wherein the melted thermoplastic elastomercompound is degassed under vacuum.
 12. The process according to claim 1,comprising employing a planetary roll extruder as said roll system. 13.A process for producing a thermoplastic elastomer compound in the formof a mixture of at least one thermoplastic elastomer compound and atleast one crosslinked rubber, said mixture being produced from thefollowing mixture components comprising: at least one thermoplastic inan amount of 10% to 90% by weight; with the balance up to 100% by weightof at least one crosslinked rubber; a crosslinking activator; and acrosslinking agent; with the use of a roll system comprising a feedingopening of a conveyor screw feeding a first roll element, additionalroll elements with feed points for adding other components in atransition area of the roll elements, whereby each roll element has amain spindle and a plurality of revolving spindles, and whereby thecomponents of the mixture are fed into the roll system via the feedingopening and the feed points; comprising the following process step:jointly feeding the thermoplastic and the crosslinked rubber and thecrosslinking agent into the roll system via the feeding opening andsubsequently melting and dispersing; dispersing the mixture andhomogenizing as vulcanization is simultaneously taking place atextension rates of 100 to 1500/s, with formation of the thermoplasticelastomer compound; whereby the calendered surface area per kilogram ofthermoplastic elastomer compound amounts to ≧75 m² based on the totalityof roll elements.
 14. The process according to claim 13, comprisingadding the crosslinking activator before the crosslinking agent isadded.
 15. The process according to claim 13, wherein the calenderedsurface area per kilogram of thermoplastic elastomer compound amounts to≧100 m², and wherein said thermoplastic elastomer compound ispolypropylene.
 16. The process according to claim 13, wherein thedivision of the crosslinking rubber particles takes place at a value ofη_(DP)/η_(CP)≧4 due to highly expanding flows as the revolving spindlesengage the screw base of the main spindle, whereby η_(DP) is theviscosity of the disperse phase and η_(CP) is the viscosity of thecontinuous phase.
 17. The process according to claim 13, wherein theextension rates amount to 500 to 1500 s⁻¹.
 18. The process according toclaim 13, wherein the dwelling time of the mixture amounts to ≦60 sbased on the totality of roll elements.
 19. The process according toclaim 13, wherein the crosslinking time of the rubber amounts to ≦30 s.20. The process according to claim 13, wherein the temperature of thethermoplastic elastomer compound at the time of exit of the compoundfrom the last roll element does not exceed the melting temperature ofthe thermoplastic material by more than 70° C.
 21. The process accordingto claim 13, wherein the roll system has an overall length of 0.8 to 6 mbased on the totality of roll elements.
 22. The process according toclaim 13, wherein the rubber is crosslinked to an extent such that notmore than 10% by weight of the rubber is soluble in a rubber solvent;and wherein the dwelling time of the mixture ranges from 10 to 30seconds based on the totality of the roll elements.
 23. The processaccording to claim 13, wherein the melted thermoplastic elastomercompound is degassed under vacuum.
 24. The process according to claim13, comprising employing a planetary roll extruder as roll system.